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1880 


AXMVKHSAKY    MKMOIRS  OK  TIIK   IIOSTON    SOCIKTY  OF  .NATOKAL   HISTORY. 


IE    IDE.XTITY 


AS(  i:\DIN(J   PROCFSS  OF  THE  ASTRAGALUS  IN  BIRDS 


WITH   THE   INTERMEDIUM. 


BY  EDWARD  S.  MOUSE,  Pn.D. 


CD 
H 
CO 

CO 


BOSTON : 

I;Y  rnn«;  SOCIKTY. 
1880. 


EXCHANGE 


BIOLOGY 

LIBRARY 

G 


1830.         ANNIVERSARY  MEMOIRS  OF  THE  BOSTON  SOCIETY  OF  NATURAL  HISTORY.          1880. 


ON  THE    IDENTITY 


or    THE 


ASCENDING  PROCESS  OF  THE  ASTRAGALUS  IN  BIRDS 


WITH  THE  INTERMEDIUM. 


BY  EDWARD  S.  MORSE,  PH.D. 
II 


BOSTON: 

PUBLISHED  BY  THE  SOCIETY. 

1880. 


,7 


BIOLOGY 

LIBRARY 

G 


ON   THE  IDENTITY  OF  THE   ASCENDING  PROCESS  OF  THE   ASTRAGALUS   IN  BIRDS  WITH 
THE   INTERMEDIUM.     BY  EDWARD   S.  MORSE. 

PROM  the  time  that  Hermann  Von  Meyer,  fifty  years  ago,  first  recognized  that  the 
Triassic  reptiles  had  characters  which  removed  them  widely  from  living  forms,  anato- 
mists and  palaeontologists  have  been  diligently  at  work  defining  with  greater  exactness 
the  anatomical  features  of  these  early  animals.  The  results  of  these  labors  have  been  to 
increase  the  distinctions  between  these  forms  and  their  supposed  living  representatives, 
and  to  erect  for  some  of  them  new  orders  in  the  old  class  of  Reptiles.  Nor  has  this  been 
the  only  result ;  through  Professor  Cope's  ( 1,  2,  3)  studies  of  the  Dinosaurs  of  the  Greensand 
of  New  Jersey,  avian  affinities  were  pointed  out  which  were  subsequently  and  independently 
confirmed  by  Professor  Huxley  (4,  5). 

With  the  gradual  unfolding  of  these  features,  .the  unquestionable  reptilian  character  of 
the  group  with  its  unmistakable  avian  pelvis  and  hind  limb  became  evident. 

The  birds  whose  affinities  with  other  classes  had  been  so  obscure  as  to  have  caused 
them  to  be  designated  as  a  dosed  type,  became  better  understood ;  for  the  key  to  their 
mysterious  affinities  was  found  in  the  rocks  of  the  Mezozoic  age,  and  in  the  transient 
features  of  their  own  embryos. 

With  the  closer  approximation  of  the  Reptiles  and  Birds  by  Huxley,  under  the  greater 
division  Sauropsida,  our  only  wonder  is  that  relationships  so  plain  had  never  before  been 
recognized.  Gegenbaur's  (6)  determination  of  the  more  important  elements  of  the  tarsus 
in  Birds,  and  the  rapid  growth  of  our  knowledge  of  the  Dinosaurians  through  the  labors 
of  Leidy,  Cope,  Marsh  and  Huxley,  have  gradually  strengthened  the  conviction  that 
among  the  Dinosaurs,  or  closely  related  forms,  we  were  to  look  for  the  progenitors  of  the 
present  birds. 

Professor  H.  G.  Seeley  (7),  in  a  lecture  on  the  Dinosauria,  delivered  before  the  Scientific 
Club  of  Vienna,  while  admitting  for  them  a  few  avian  characters,  considers  that  some 
relations  have  been  overrated,  and  that  the  avian  affinities  of  the  Dinosaurians  were  not 
so  strong  as  had  been  supposed.  It  seems  to  me,  however,  that  he  does  not  give  sufficient 
importance  to  the  fact  that  some  of  these  relations  have  been  based  on  the  characters 
presented  by  birds  in  an  advanced  stage  of  embryonic  growth,  that  is  to  say  in  embryos 
so  far  advanced,  that  all  the  leading  avian  features  had  been  established. 

While  Professor  Seeley  admits  certain  avian  characters  in  the  hind  limbs  of  some 
Dinosaurians,  he  says  that  they  are  limited  to  two  points :  "  First,  the  development  of  a 
strong  anterior  crest,  which  is  directed  forward  and  outward,  so  as  to  extend  in  front  of 


299222 


4  EDWARD   S.  MORSE  ON 

the  fibula,  is  a  Dinosaurian  character  met  with  to  some  extent  among  birds,  but  quite  as 
well  marked  in  mammals.  Secondly,  the  shape  of  the  distal  end  of  the  bone  is  birdlike  ; 
but  that  form  is  found  in  no  adult  bird,  and  is  only  to  be  detected  in  the  young 
bird  before  the  tarsus  had  become  blended  with  it,  so  that  while  it  might  go  to  show, 
perhaps,  that  birds  are  descended  from  a  common  stock  with  Dinosaurs,  it  would  be 
misleading  to  regard  it  as  altogether  avian,  since  the  character  is  lost  in  the  adult  bird's 
skeleton"  (page  57).  And  furthermore,  he  says,  "But  when  the  tarsus,  or  rather,  the 
astragalus,  is  closely  applied  to  the  tibia,  as  in  Megalosaurus,  Poecilopleuron,  Laelaps, 
or  Iguanodon,  it  gives  the  bone  a  resemblance  to  the  birds  which  is  almost  convincing, 
since  the  parallel  extends  to  nearly  every  detail.  The  character,  however,  is  shorn  of 
much  of  its  importance,  when  we  remember  that  there  are  many  Dinosaurs  in  which 
there  is  an  os  calcis,  or  heel-bone,  placed  side  by  side  with  the  astragalus." 

Professor  Seeley  is  aware  that  in  Laelaps  the  hour-glass  shaped  tarsal  bone  represents 
the  os  calcis  and  astragalus  connate  ;  also  that  Prof.  Cope  shows  that  these  two  bones  are 
ankylosed  in  Ornithotarsus. 

The  memoir  of  Gegenbaur  on  the  Tarsus  and  Carpus  of  Birds  had,  for  the  moment, 
probably  escaped  the  attention  of  Prof.  Seeley.  In  this  contribution  of  Gegenbaur's  the 
separation  of  the  tarsal  portion  into  two  bones,  the  upper  and  under  tarsal  bone,  is  clearly 
pointed  out.  Furthermore,  Gegenbaur  shows  two  centres  of  ossification  in  the  upper, 
or  proximal  bone,  which  he  rightly  infers  to  represent  the  tibiale  and  fibulare  (these 
names  are  used  in  preference  to  those  of  astragalus  and  os  calcis,  as  better  denning  the 
relations  existing  between  them  and  the  tibia  and  fibula).  These  demonstrations  were 
based  on  an  examination  of  the  chick  at  a  late  stage  of  embryonic  growth. 

In  my  memoir  (8),  on  the  Tarsus  and  Carpus  of  Birds,  I  not  only  fully  confirmed 
the  observations  of  Gegenbaur,  but  showed  the  absolute  separation  of  these  two 
elements  as  tibiale  and  fibulare,  based  on  an  examination  of  a  number  of  species  of  birds 
at  an  earlier  stage  than  those  examined  by  Gegenbaur.  Figures  of  these  were  also  given, 
showing  the  fibula,  with  the  same  length  as  the  tibia,  and  nearly  approximating  to  the 
fibulare. 

While  preparing  the  memoir  above  alluded  to,  Prof.  Wyman  kindly  sent  me  some 
observations"  of  his  on  the  tarsus  of  the  embryo  Heron,  which  he  generously  allowed  me 
to  incorporate  with  my  paper.  Briefly,  these  consisted  in  his  finding  a  long  style- 
shaped  bone,  broadest  at  its  distal  extremity,  lying  in  front,  and  at  the  distal  end  of  the 
tibia,  which  he  believed  to  represent  the  so-called  ascending  process  of  the  astragalus, 
but  which  was  shown  to  have  an  independent  centre  of  ossification  in  the  embryo,  and 
to  remain  free  from  the  other  tarsal  bones  till  the  young  had  left  the  egg ;  when 
it  appeared  attached  to  the  coessified  tibiale  and  fibulare,  and  presented  the  appearance 
not  unlike  that  shown  by  Huxley  in  the  young  ostrich. 

My  interpretation  at  the  time  was  that  this  new  tarsal  bone  represented  the  inter- 
medium, a  tarsal  bone  which  is  clearly  seen  in  the  salamanders  as  occupying  a  position 
between  the  tibia  and  fibula,  and  indeed  with  half  its  length  forced  up,  as  it  were,  between 
these  two  bones. 

I  have  previously  shown  that  as  the  proximal  series  of  tarsal  bones  became  united,  the 
fibula  diminished  in  size  proportionally  with  the  rapid  increase  of  the  tibia,  and  became 


THE  INTERMEDIUM  IN  BIRDS.  5 

finally  a  splint  bone,  with  its  attenuated  distal  extremity  far  removed  from  the  tarsus  ;  the 
tibia  on  the  contrary,  enlarging,  so  that  its  distal  extremity  equalled  in  transverse 
diameter  the  two  tarsal  bones,  which  formed  a  cap  on  the  end  of  the  tibia,  like  an 
epiphysis,  and  finally  became  merged  with  it.  The  intermedium,  while  occupying  its 
proper  position  between  the  tibiale  and  fibulare,  and  finally  uniting  with  them,  became 
apparently  displaced,  so  to  speak,  by  standing  in  front  of  the  tibia. 

This  could  be  stated  at  the  time  with  certainty :  Namely,  that  the  ascending  pro- 
cess of  the  astragalus  was  an  independent  bone,  which  finally  united  with  the  proxi- 
mal series  of  tarsal  bones,  and  that  a  similar  process  in  the  young  chick  and  ostrich,  as 
figured  by  Huxley,  and  a  similar  spur  or  process  as  seen  in  the  astragalus  of  Laelaps  and 
some  other  Dinosaurs,  was  to  be  looked  upon  as  of  the  same  nature. 

To  prove  the  correctness  of  this  interpretation  as  to  whether  this  bone  was  the  inter- 
medium, it  was  necessary  to  examine  the  early  embryo,  and  to  find,  if  possible,  the  bone 
occupying  its  true  position  in  the  tarsal  series,  and  between  the  distal  extremity  of  the 
tibia  and  fibula. 

Believing  that  low  aquatic  birds  would  more  readily  yield  these  evidences,  a  visit  was 
made  to  Grand  Menan,  at  the  mouth  of  the  Bay  of  Fundy,  and  at  that  place  were 
obtained  the  embryos  of  the  razorbill  auk,  eider  duck,  sea  pigeon,  herring  gull  and 
petrel. 

At  Penikese  Island  in  Buzzard's  Bay,  an  opportunity  was  offered  of  examining  the 
embryos  of  the  tern.  Through  the  courtesy  of  the  Smithsonian  Institution,  I  had  the 
gratification  of  examining  embryos  of  the  southern  black-backed  gull,  and  the  large 
penguin  collected  by  Dr.  Kidder  at  Kerguelen  Island,  during  the  U.  S.  Transit  of  Venus 
Expedition,  and  the  results  of  these  examinations  were  communicated  verbally  at  the 
meetings  of  the  American  Association  for  the  Advancement  of  Science  in  1874  (9)  and 
1875. 

With  the  hope  of  making  these  observations  more  complete,  their  publication  was 
withheld  at  the  time.  Finding  the  opportunity  of  studying  other  aquatic  birds  still 
uncertain,  these  results,  slight  though  they  may  be,  are  given. 

The  accompanying  plate  presents  in  outline  the  tarsal  joint  of  the  following  birds: 
The  common  Tern,  Sterna  hirundo  ;  Petrel,  Procellaria  pelagica ;  Eider  Duck,  Somateria 
mollissima ;  Sea  Pigeon,  Uria  grylle  ;  Common  Guillemot,  Lomvia  troile ;  Herring  Gull, 
Larus  aryentatus ;  Razor  bill  Auk,  Utamania  torda ;  Southern  black  backed  Gull,  Larus 
dominicanus,  and  Great  Auk,  Aptenodytes  Pennanti. 

An  additional  figure  is  added  of  the  right  hand  limb  of  the  Sea-pigeon,  as  it  shows  the 
appearance  of  rudimentary  nails  on  the  second  and  third  fingers. 

In  the  figures  of  Sterna  hirundo,  figs.  1-4),  different  stages  of  the  tarsus  are  represented. 
Fig.  1  shows  the  intermedium  distinctly  wedged  between  the  tibia  and  fibula,  with 
its  distal  end  in  line  with  the  distal  margins  of  the  tibiale  and  fibulare.  The  centrale 
is  still  small.  In  a  later  stage,  as  represented  in  figs.  2,  3,  and»4,  the  tibia  has  widened 
considerably,  though  the  tibiale  and  fibulare  have  not  yet  united.  The  intermedium 
now  appears  in  front  of  the  tibia,  though  still  on  a  line  with  the  tibiale.  The  separation 
of  the  distal  end  of  the  fibula  and  its  tarsal  bone  has  increased.  The  centrale  has 
slightly  increased  in  size.  In  fig.  2,  the  tibiale  and  fibulare  have  coalesced.  The 


6  EDWARD   S.  MORSE  ON 

intermedium  has  been  crowded  out  and  up,  so  that  its  distal  end  is  on  a  line  with 
the  proximal  margin  of  the  tibiale  and  fibulare.  The  centrale  has  increased  in  size 
so  that  its  transverse  diameter  is  equal  to  that  of  the  three  metatarsals,  to  which  it  finally 
becomes  attached  at  a  later  stage. 

In  the  Petrel,  Procellaria  pelagica,  fig.  5,  a  stage  is  represented,  similar  to  that 
of  the  Tern,  fig.  2.  A  new  tarsal  bone  appears,  (indicated  on  the  plate  with  a 
question  mark),  corresponding  to  the  rudimentary  first  toe.  This  bone  was  clearly  defined 
in  both  legs.  In  appearance  it  looks  like  the  proximal  end  of  the  first  metatarsal  bone, 
with  its  corresponding  tarsal.  In  only  one  other  bird  has  a  bone  at  all  resembling 
this  been  seen,  and  that  is  shown  in  the  figure  of  the  Eider  Duck  (fig.  8,  indicated 
by  a  query  mark).  In  this  case  it  appears  like  a  second  tarsale.  In  both  cases  this 
bone  appears  on  the  tibial  side  of  the  leg.  It  will  be  unsafe  to  hazard  a  conjecture 
as  to  what  this  bone  represents,  without  further  examination  of  other  species. 

In  the  Sea  Pigeon,  Uria  grylle,  the  intermedium  is  a  prominent,  wedge-shaped  bone, 
and  quite  separate  from  the  other  tarsal  bones,  though  the  embryo  was  far  advanced. 
Its  large  size  is  interesting  in  connection  with  the  fact  that  the  fore  limb  shows 
conspicuous  rudimentary  nails  on  the  second  and  third  fingers.  (See  figs.  11,  12.) 

In  fig.  8,  the  tarsus  and  a  portion  of  the  other  bones  of  the  leg  of  the  Eider  Duck, 
Somateria  mollissima,  are  represented.  In  this  embryo  the  intermedium  was  clearly  seen 
between  the  tibia  and  fibula,  the  tibiale  and  fibulare  being  widely  separated. 

In  the  Herring  Gull,  Larus  argentatus,  the  intermedium  is  not  large,  the  near  tarsal 
bones  are  about  uniting,  yet  the  intermedium  is  still  free,  and  somewhat  removed  from 
them. 

In  the  Southern  Black  backed-Gull,  Larus  dominicanus,  the  intermedium  is  in  nearly 
the  same  condition.  In  the  Great  Auk,  Aptenodytes  Pennanti,  the  appearance  of  the 
very  short  metatarsal  bones,  and  the  short  square  phalangeal  bones,  is  extremely  inter- 
esting. The  embryo  was  far  advanced,  as  indicated  by  the  long  and  prominent  claws 
tipping  the  toes.  Yet  the  bones  composing  the  foot  are  very  rudimentary. 

The  embryo  of  this  species,  and  also  that  of  the  Southern  Black-backed  Gull,  had  been 
preserved  in  strong  alcohol  for  several  years,  and  the  cartilaginous  portion  of  the  tarsus 
was  so  opaque  that  nothing  definite  could  be  made  out  in  regard  to  the  other  tarsal  bones. 
The  intermedium,  however,  in  both  species,  was  very  distinct. 

From  these  observations  it  is  seen  that  the  intermedium  is  present  in  embryo  birds  as  a 
distinct  tarsal  bone  ;  that  at  first  it  is  in  line  with  the  near  tarsal  series,  that  is  to  say 
with  the  tibiale  and  fibulare,  and  also  between  these  two  bones,  and  consequently 
between  the  distal  extremities  of  the  distal  ends  of  the  tibia  and  fibula.  As  the  tibiale 
and  fibulare  coalesce,  the  intermedium  is  crowded  outward  and  upward,  the  tibia  widening 
at  the  same  time  to  an  extent  equal  to  the  transverse  diameter  of  the  near  tarsal  series ; 
the  intermedium  occupies  a  position  in  front  of  the  tibia,  and  fills  a  groove  which  is  seen 
on  the  anterior  face  of  the  tibia.  It  is  seen,  furthermore,  that  the  intermedium  is  the 
last  bone  to  unite  with  the  coossified  tibiale  and  fibulare. 

The  intermedium  varies  greatly  in  size  in  the  embryos  of  different  species.  It  will 
probablv  be  found  of  more  common  occurrence  among  the  lower  birds. 


THE  INTERMEDIUM  IN   BIRDS.  7 

In  young  birds  of  certain  species  it  is  seen  as  an  ascending  spur  occupying  the  fossa  on 
the  lower  anterior  face  of  the  tibia.  In  mature  birds,  as  far  as  I  have  discovered,  it 
becomes  absorbed. 

The  wide,  oblique,  tendon -like  bridge,  which  spans  the  fossa  in  the  heron  and  many 
other  birds,  has  no  relation  with  the  intermedium. 

In  Laelaps  and  some  other  Dinosaurian  Reptiles,  this  bone  is  seen  as  an  ascending  spur 
of  the  coossified  tibiale  and  fibulare.  In  Ornithotarsus,  as  figured  by  Professor  Cope,  an 
appearance  of  the  tarsus  is  represented,  which  is  not  unlike  that  shown  in  the  early 
stages  of  the  Tern.  See  plate,  fig.  1. 

It  is  possible  that  the  intermedium  in  Ornithotarsus  was  a  separate  bone,  and  that  it  has 
been  lost  in  the  fossil,  as  a  distinct  grove  or  fossa  is  seen  on  the  lower  anterior  face  of 
the  tibia,  while  no  corresponding  spur  is  seen  on  the  tibiale,  a  slight  elevation  only  being 
discernible. 

Professor  Marsh  (10),  in  a  paper  on  the  Limbs  of  Sauranodon,  an  animal  related  to 
Ichthyosaurus,  has  presented  some  novel  views  in  regard  to  the  homologies  of  the 
intermedium. 

cf  The  fee  limb  is  there  figured  with  the  femur  of  the  usual  character.  Its  distal  face 
having,  however,  three  articular  surfaces,  to  which  are  applied  three  bones  in  the  shape 
of  irregular  formed  disks ;  these  he  interprets  as  tibia,  intermedium  and  fibula. 

He  suggests  that  the  intermedium  belongs  to  the  epipodial,  or  second  series  of  bones 
represented  by  the  radius  and  ulna,  and  tibia  and  fibula,  and  that  in  the  process  of  differ- 
entiation the  intermedium  has  been  crowded  down  into  the  mesopodial  or  first  series  of 
tarsal  bones. 

My  interpretation,  based  on  the  admirable  figure  he  presented,  would  be  that  the  bone 
which  he  indicates  as  the  intermedium  is  really  the  fibula,  and  the  bone  which  he  repre- 
sents as  the  fibula,  is  an  outer  tarsal  bone,  which,  with  its  metatarsal  and  phalangeal 
bone  in  series  becomes  obliterated  in  time;  that  in  the  process  of  differentiation  the 
intermedium  is  as  likely  to  be  partially  compassed  by  the  distal  extremities  of  the  tibia 
and  fibula,  as  that  a  third  bone  of  this  segment  had  been  crowded  down  into  the  tarsal 
series.  However  this  may  be,  Professor  Marsh  has  discovered  a  most  interesting  stage  in 
this  highly  primitive  condition  of  the  bones  as  shown  in  Sauranodon. 

In  the  following  outlines,  figures  are  presented  of  a  portion  of  the  leg  of  a  salamander, 
a  number  of  embryo  birds,  young  birds,  and  Dinosaurian  reptiles.  These  are  given  in 
series,  so  that  a  comparison  may  be  made  between  the  different  stages  of  the  inter- 
medium in  each  of  these  forms.  In  the  first  series,  figs.  1,  2,  3,  4,  the  intermedium 
is  seen  as  a  separate  bone.  In  the  second  series  the  intermedium  has  united  with  the 
other  tarsal  bones  and  assumes  the  appearance  which  has  been  described  as  the  ascending 
process  of  the  astragalus.  In  the  third  series  a  similar  condition  is  seen. 

For  explanation  of  lettering,  see  explanation  of  plate.  The  lettering  being  the  same 
with  the  exception  that  tf  indicates  the  tibiale  and  fibulare  connate. 


EDWARD   S.  MORSE   ON 


ADULT  SALAMANDER  AND  EMBRYO  BIEDS. 


Fig.  l. 
Salamander. 


Fig.  2. 
Tern. 


Fig.  3. 
Sea  Pidgeon. 


Fig.  4. 
Blue  Heron. 


Fig.  1.  Fore  leg  of  Salamandra  maculosa,  showing  the  intermedium,  i,  in  its  position 
between  the  distal  ends  of  the  tibia  and  fibula. 

Fig.  2.  Portion  of  leg  of  common  Tern  from  an  embryo,  showing  the  appearance  of 
the  intermedium  between  the  distal  ends  of  the  tibia  and  fibula. 

Fig.  3.  Portion  of  leg  of  the  Sea  Pigeon  from  an  embryo  with  the  intermedium  in 
front  of  the  tibia,  from  the  widening  of  the  tibia  so  as  to  compass  in  width  the  tarsal 
bones. 

Fig.  4.  Distal  extremity  of  the  tibia  of  the  Blue  Heron  from  an  advanced  embryo. 
In  this  figure  only  the  intermedium  is  shown.  Its  distal  end  had  not  yet  coossified  with 
the  other  tarsal  bones. 


YOUNG  BIRDS. 


Fig.  5. 


Fig.  6. 


Fig.  7. 


Fig.  8. 


Fig.  9. 
Young  Blue  Heron. 


Young  Ostrich.  Young  Fowl. 

Figs.  5  and  6.  Front  and  side  views  of  the  distal  end  of  the  tibia  and  tarsus  of  a 
young  ostrich.  From  a  figure  of  Professor  Huxley's  in  Quarterly  Journ.  Geological  Soc., 
above  referred  to.  These  figures  show  the  tarsal  bones  including  the  intermedium 
ankylosed  together ;  the  intermedium  appearing  as  an  ascending  spur  or  process  of  the 
other  tarsal  bones. 

Figs.  7  and  8.  Front  and  side  views  of  the  distal  end  of  tibia  and  tarsus  of  a  young 
fowl,  from  Huxley's  Anatomy  of  Vertebrated  Animals,  p.  253,  fig.  88.  The  condition 
and  general  appearance  are  the  same  as  in  the  figures  of  the  young  ostrich. 


THE  INTERMEDIUM  IN  BIRDS.  9 

Fig.  9.  Side  view  of  the  distal  end  of  tibia  and  tarsus  of  a  young  Blue  Heron. 
The  intermedium,  as  in  the  case  of  the  young  Ostrich  and  young  fowl,  has  the  appearance 
of  an  ascending  spur  from  the  other  tarsal  bones. 

DIXOSAUKIAN  REPTILES. 


Fig.  10. 
Ornithotarsus. 


Fig.  11. 
The  "Hun/leur  Reptile." 


Fig.  12. 
Laelaps. 


Fig.  10.  Distal  extremities  of  the  tibia  and  fibula  of  Ornithotarsus,  after  Cope's  figure 
in  Trans.  Amer.  Phil.  Soc.,  Vol.  xiv,  fig.  35,  page  122.  The  tibiale  and  fibulare  are 
coossified.  Whether  the  intermedium  is  represented  by  the  enlargement  of  the  tibiale 
in  front,  or  was  a  separate  bone  which  occupied  the  fossa  on  the  anterior  face  of  the  tibia, 
is  a  matter  of  doubt.  Ornithotarsus  certainly  presents  a  number  of  features  that  warrants 
its  name. 

Fig.  11.  Distal  end  of  tibia  and  tarsus  of  the  "  Honfleur  Reptile,"  reduced  from  a 
figure  in  Cuvier's  Ossemens  Fossiles,  described  by  Cuvier  under  the  general  head  of 
Megalosaurus,  without  identification,  afterwards  named  by  Cope  Laelaps  gallicus.  The 
intermedium  is  seen  as  a  blunt  portion  ascending  from  the  other  tarsal  bones. 

Fig.  12.  Distal  end  of  tibia  and  tarsal  bones  of  Laelaps;  side  view.  Reduced  from 
Cope's  figure  in  Trans.  Amer.  Phil.  Soc.,  Vol.  xiv.,  plate  9.  In  this  figure  the  intermedium 
is  again  seen  as  a  long  ascending  spur  in  front  of  the  tibia,  but  the  coossified  tibiale  and 
fibulare  occupy  a  far  different  position  in  relation  to  the  distal  articular  face  of  the  tibia 
from  what  is  seen  in  birds. 


WORKS  REFERRED  TO. 

1.  On  the  Anomalous  Relations  existing  between  the  Tibia  and  Fibula  in  certain  of  the  Dinosauria  as 
illustrated  by  the  genus  Laelaps.     Prof.  Cope.    Proc.  Philad.  Acad.  of  Sciences,  Dec.  1866,  p.  317. 

2.  An  Account  of  the  Extinct  Reptiles  which  approach  the  Birds.    Prof.  Cope.    Proc.  of  the  Philad. 
Acad.  of  Sciences,  Dec.  18G7,  p.  234. 

3.  Synopsis  of  the  Extinct  Batrachia,  Reptilia  and  Aves  of  North  America.    Prof.  Cope.    Transactions 
of  the  American  Philosophical  Society,  read  Sept.  18,  1808,  and  April  2,  1869. 


10  MORSE   ON  THE   INTERMEDIUM  IN  BIRDS. 

4.  On  the  Animals  which   are  most  Intermediate  between  Birds  and  Reptiles.     Prof.  Huxley.    The 
Popular  Science  Review,  No.  xxvm,  p.  237 ;  being  a  Lecture  delivered  before  the  Royal  Institution,  Feb.  7- 
1868. 

5.  Further   Evidence  of  the  Affinity  between   the  Dinosaurian  Reptiles  and  Birds.     Prof.  Huxley. 
Quart.  Journ.  Geological  Soc.  of  London.    Vol.  xxvi.    1870. 

6.  Untersuchungeu  zur  vergleichenden  Anatomie  der  Wirbeltheire.    Erstes  Heft ;  Carpus  und  Tarsus. 
Prof.  Gegenbaur.     Leipzig,  1864. 

7.  The  Dinosauria.    Prof.  Seeley.    The  Popular  Science  Review,  Jan.  1880,  p.  44;  being  originally  a 
Lecture  delivered  at  the  Scientific  Club  at  Vienna,  on  the  19th  of  April,  1879. 

8.  On  the  Tarsus  and  Carpus  of  Birds.    E.  S.  Morse.    Annals  of  the  Lyceum  of  Nat.  Hist.  N.  Y.,  vol.  10 
Art.  vin.     Read  Jan.  29,  1872. 

9.  On  the  Ascending  Process  of  the  Astragalus  in  Birds.    E.  S.  Morse.    Meeting  of  the  American  Asso- 
ciation for  the  Advancement  of  Science.    Hartford,  1874. 

10.  On  the  Limbs  of   Sauranodon.     Prof.  Marsh.    American  Journal  of   Science   and  Arts,  vol.  xix, 
Feb.  1880. 

EXPLANATION  OF  PLATE  I. 

Fig.  1.     Portion  of  left  leg  of  embryo  Tern. 

jpjg_  2.          "        "     «     «     «       «  " 

Fig.  3.          «        «     «     «     «       «  <c 

!•' jo-_  4.          "        "     "     "     "       "  " 

Fig.  5.    Portion  of  right  leg  of  embryo  Petrel. 

Fig.  6.          "        "    left      "     "       "         Sea  Pigeon. 

Fig.  7.  "        "     "         "     "       "        Herring  Gull. 

Fig.  8.  "        "     "        "     "       "        Eider  Duck. 

Fig.  9.          "        "    right  "     "       "         Southern  black-back  Gull. 

Fig.  10.        "        "      "       "     "       "        Penguin. 

Fig.  11.         "        "    right  wing  of  embryo  Sea  Pigeon. 

Fig.  12.         "        "      "          "     "        "         "          "        third  finger  more  enlarged. 

EXPLANATION  OF  LETTERS. 

Fe,  femur ;  T,  tibia ;  f,  fibula ;  t,  tibiale ;  /,  fibulare ;  Jj  intermedium ;  c,  centrale  ;  ?  tarsal  bone  of  the 
second  series  ?  D,  ulna  ;  H,  radius  ;  u,  ulnare  ;  r,  radiale  ;  3,  4,  third  and  fourth  carpal  bones  ;  I,  II,  III,  IV, 
metacarpals. 


Annivers  Memoirs  Bost.  Soc.  Nat.  Hist. 


Morse,  PI.  I. 


T       , 


E.S.M.  a3  nat 


.  UTH  BOSTOM 


THE   INTERMEDIUM    IN    BIRDS. 


299222 


Bio; 

LIBRAKY 
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